Thursday, May 5, 2016

Why is it 2016?

According to the A-theory, it's an objective but contingent fact about the world that it's the year 2016. What explains this contingent fact about the world? I've argued against the A-theory along these lines before, but I want to try a somewhat different tack right now. The most plausible explanation is:

It's 2016 because a year ago it was 2015.

But what kind of explanation is (1)? I know of three kinds of explanations of contingent facts. First, there are causal explanations, where we explain a fact by giving a cause of it. Second, there are grounding or constitutive explanations, where we explain a fact by giving a ground of it. Third, there are nomic explanations, where we explain a fact by giving a law of nature and initial conditions (I think this is a special case of causal explanations, but that's a different question).

Which of these is (1) an example of? It doesn't seem causal. Its having been yesterday a day ago doesn't cause it to be today. Events yesterday may have caused there to be a today, but they don't cause the A-theoretic fact of its being today. It also doesn't seem to be constitutive. Its being 2016 isn't constituted by its having been 2015 a year ago. Nor does the connection between its having having been 2015 a year ago and its being 2016 now seem to be merely nomic. It's both metaphysically necessary and a priori that if it was 2015 a year ago, then it's 2016.

Of course, the A-theorist can say that (1) is an instance of a sui generis kind of explanation. But types of explanation should not be multiplied beyond necessity, and a type of explanation that applies only in one narrow set of cases seems ad hoc.

11 comments:

It isn't really 2016 right now. That's a naming convention. Now, the series of causes prior to now which have led up to this way of naming years, and the chain of doing that for the past however-many years, has causally produced the effect of all of us CALLING the current year 2016. So, the answer to your question is, in some sense, the first option: causation. But that doesn't make it BE 2016 (which it isn't for, say, the Chinese calendar), it just explains by causal chain why we currently SAY it is 2016.

I think that's a false analogy. You are a particular person among other people. On the A-theory, there are no other current years. There's just a way of talking about the present, and what causes us to say that it is now 2016 is the chain of causes going back to previous years, etc.

That may have been unclear. What I mean is that we are well aware that our naming system for years is utterly arbitrary, and comes from a chain of causes historically. But it is always only NOW; this present year. All that changes is what we call the present, and that act of calling the present something or other can be traced to a chain of causes.

It's like days of the week. It is only Thursday right now because we called it "Wednesday" yesterday, and so on back to the first time we called days by names. But no one thinks that Thursdays actually exists as an objective reality. It's just the present. The only present. Our act of calling it something is a social convention that has a clear chain of causation leading up to it.

The cosmological argument has a principle that there cannot be infinite regresses of explanation. But explanations of the form of (1) would suffer from such a regress; there would just be the question of why it was 2015 a year ago. Then 2014, 2013, etc.

So if the no-infinite-regresses principles are accurate, (1) is not a legitimate (or at least, complete) explanation.

Thanks for the post—this is interesting. I am no fan of the A-theory, but I wonder whether they might be able to make sense of this in terms of causal explanation. Instead of discussing a year (2016), let’s discuss a smaller period of time. For the sake of the discussion, let us suppose that we can speak in terms of instants. Perhaps the present is only one instant long, or perhaps, as thick-presentists have it, it is longer. Now, whether instantaneous or thick, our present is a time-slice. The only actual time-slice, as a-theorists would have it. Further, they might say that it is a necessary truth that all actual time-slices are current time-slices. Thus, to explain why this time-slice is present, we need only explain why it is actual. To do this, we can appeal to a causal explanation, and to do that, we can appeal to the previous time-slice that caused this one. We might still think we need an explanation of why this time-slice hasn’t gone out of existence, but then we can just simply note that time-slices only go out of existence when they cause another to come into existence (perhaps this will need further explanation if time can end), and this time-slice hasn’t yet caused another to come into existence. I don’t see a way to make this work nicely given the relativity of simultaneity, but that is an issue for presentists anyway.

Well, given the other usual premise of the cosmological argument (that things don't come into being without causes), it would seem to me that there is a straightforward causal answer to that question, no?

Your explanation makes sense, and given that GTR doesn't have reference frames for simultaneity to be relative to, I don't see the problem. There's a huge disconnect (in my opinion) when people keep talking about reference frames after moving from STR to GTR. Besides, even if we still were stuck with STR, there is a Neo-Lorentzian formulation of it which is friendly to the A-theory. So, any A-theorist who thinks she has sufficient justification for the A-theory, has thereby a defeator for standard STR and evidence for Neo-Lorentzian views.

There are reference frames in two senses in GTR: (1) there is a local (in the limit of small scale) Lorentzian reference frame at each observer (2) there is a global frame-like thing provided by any foliation by spacelike hypersurfaces.

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